Magnitude 3.7 earthquake rattles southern and central Ontario

Thousands of southern and central Ontario residents are reporting that they were shaken by an earthquake late Tuesday night, according to Natural Resources Canada.

Earthquakes Canada recorded a magnitude 3.7 quake about 99 kilometres northeast of Toronto just before 11 p.m. ET.

The agency noted the “lightly felt” tremor was centered 23 kilometres southeast of Orillia, Ont. and occurred at a depth of five kilometres.

So far 2,600 people have reported feeling the earthquake from as far as Kingston to Kitchener, said Natural Resources Canada seismologist Marikah Adams, adding more reports are still coming in.

A “roaring sound” came crashing through her home the moment the quake struck, said Sarah Cowley, a Beaverton-based artist.

“Now I live in an old home. It’s 120 years old. It’s sturdy, but all the floors were shaking,” she said, adding it looked as if nothing had happened when she peeked out her window to check for fallen trees or other damage.

Cowley said while she was shaken by the events, her husband slept soundly through the ordeal.

The site’s “Did you feel it?” link had at least 2,000 reports of people feeling the rumble, from as far west as Kitchener, through Toronto, and east to Belleville, and as far south as Niagara Falls.

There was no immediate word on any damage or injuries, but according to statistics from Earthquakes Canada, the same area has experienced two earthquakes of similar size in the last 25 years and the largest was a magnitude 5.5 quake in 1929.

What caused the quake?

It’s not typical for this area to have any seismic activity, as it’s an intraplate region in the middle of the North American plate, said Adams.

“We don’t know if there’s going to be any follow-up events, but it’s highly unlikely,” she said.

The cause of earthquakes in this region aren’t as well understood as opposed to plate boundary regions, said Adams. But she said it might have been due to either regional stress fields or old buried faults that reactivated along zones with crustal weakness.

Pressure can build overtime near old faults, or buried cracks in the tectonic plate, that can release in “crackles,” said Lindsay Schoenbohm, geologist and associate producer at University of Toronto.

She said these small events are known as “snap, crack, pop earthquakes.”

While earthquakes might be “rare” in this region, Adams said it serves as a good reminder that they can happen anywhere and people should not panic.

“A good thing to remember if you do experience an earthquake to stop, drop, cover and hold on,” she said, adding people inside should go under a heavy table or bed and anyone outside should stay away from buildings.

Schoenbohm says it’s no longer advised that people stand under a doorway during an earthquake, which was based on an old story of someone who allegedly survived an event that way.

She said every earthquake is an opportunity to learn for scientists and will help predict future events.

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Social media was abuzz with people commenting that the quake was just the latest challenge for the region, which has recently experienced extreme snow and cold.

For Cowley, the events of this past week serve as a reminder to respect mother nature “and what she is capable of doing.”

“There are some things we can control and some things we can’t,” she said.

U.S. versus Canada earthquake reports

The U.S. Geological Survey (USGS) recorded Tuesday’s event as a magnitude 4.1 earthquake that happened at a depth of 11.5 kilometres — a measurement that’s slightly different from Earthquakes Canada’s numbers.

The difference in reports may be due to different stations being used to locate the quake or a difference in magnitude scales, said seismologist Stephen Crane with Natural Resources Canada.

He said the USGS does not have access to the stations obtaining data in Canada and that it used a different measurement scale.

That makes Earthquakes Canada the “authoritative source” for any quakes within the country and should be the go-to source for residents, said Crane.

CBC News reached out to the USGS for comment.